This invention relates to a method of detecting defects such as foreign matters, scratches and cracks included in bottles such as beer bottle and juice bottles, and to an apparatus for practicing the method.
A variety of techniques have been proposed in the art in which a bottle under inspection is conveyed while being spun, and the optical image of the bottle is converted into electrical signals from which defects included in the bottle are detected. One example of the techniques is disclosed in Japanese Patent Application No. 120073/1978 which has been filed by the present applicant. The technique disclosed therein has advantages over the techniques known before. It is however sometimes felt that the technique is sometimes insufficient in reliability.